FlexASIO fails to initialize when there are no input devices

[dechamps]

I have observed this while testing FlexASIO with an audio-over-RDP setup in a VM, which doesn't provide any input audio devices at all:

C:\Program Files\FlexASIO\x64>FlexASIOTest_x64.exe
ASIOInit(asioVersion = 2)
-> -1000 [ASE_NotPresent]
asioVersion = 2 driverVersion = 2 name = No ASIO Driver errorMessage = Unable to get device info for device index -1 sysRef = 0000000000000000

Log:

2018-11-18T12:59:23.8776000-00:00 3800 3816 Logfile opened
2018-11-18T12:59:23.8776000-00:00 3800 3816 Log time source: GetSystemTimeAsFileTime
2018-11-18T12:59:23.8776000-00:00 3800 3816 FlexASIO Release x64 0.5a-27-g69668c7 built on 2018-11-18T13:44:27.4696851+00:00
2018-11-18T12:59:23.8776000-00:00 3800 3816 Host process: C:\Program Files\FlexASIO\x64\FlexASIOTest_x64.exe
2018-11-18T12:59:23.8776000-00:00 3800 3816 --- ENTERING CONTEXT: CFlexASIO()
2018-11-18T12:59:23.8776000-00:00 3800 3816 --- EXITING CONTEXT: CFlexASIO() [OK]
2018-11-18T12:59:23.8786000-00:00 3800 3816 --- ENTERING CONTEXT: init()
2018-11-18T12:59:23.8786000-00:00 3800 3816 Attempting to load configuration file: "C:\\Users\\test\\FlexASIO.toml"
2018-11-18T12:59:23.8786000-00:00 3800 3816 Unable to open configuration file: ios_base::failbit set: iostream stream error
2018-11-18T12:59:23.8786000-00:00 3800 3816 PortAudio version: PortAudio V19.6.0-devel, revision 396fe4b6699ae929d3a685b3ef8a7e97396139a4
2018-11-18T12:59:23.8786000-00:00 3800 3816 Enabling PortAudio debug output redirection
2018-11-18T12:59:23.8786000-00:00 3800 3816 Initializing PortAudio
2018-11-18T12:59:23.8796000-00:00 3800 3816 [PortAudio] before paHostApiInitializers[0].
2018-11-18T12:59:23.8976000-00:00 3800 3816 [PortAudio] after paHostApiInitializers[0].
2018-11-18T12:59:23.8976000-00:00 3800 3816 [PortAudio] before paHostApiInitializers[1].
2018-11-18T12:59:23.9046000-00:00 3800 3816 [PortAudio] Cannot create Capture for Primary Sound Capture Driver. Result = 0x88780078
2018-11-18T12:59:23.9196000-00:00 3800 3816 [PortAudio] PA - PlatformId = 0x2
2018-11-18T12:59:23.9196000-00:00 3800 3816 [PortAudio] PA - MajorVersion = 0x6
2018-11-18T12:59:23.9196000-00:00 3800 3816 [PortAudio] PA - MinorVersion = 0x1
2018-11-18T12:59:23.9326000-00:00 3800 3816 [PortAudio] PA - PlatformId = 0x2
2018-11-18T12:59:23.9326000-00:00 3800 3816 [PortAudio] PA - MajorVersion = 0x6
2018-11-18T12:59:23.9326000-00:00 3800 3816 [PortAudio] PA - MinorVersion = 0x1
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] after paHostApiInitializers[1].
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] before paHostApiInitializers[2].
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI: device idx: 00
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI: ---------------
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI:0| name[Remote Audio]
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI:0| form-factor[0]
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI: getting Windows version with GetVersion()
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI: Windows version = 2
2018-11-18T12:59:23.9336000-00:00 3800 3816 [PortAudio] WASAPI: IAudioClient version = 1
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] WASAPI:0| def.SR[44100] max.CH[2] latency{hi[0.050000] lo[0.003000]}
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] WASAPI: initialized ok
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] after paHostApiInitializers[2].
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] before paHostApiInitializers[3].
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] Setup called
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] Enum called
2018-11-18T12:59:23.9366000-00:00 3800 3816 [PortAudio] Interfaces found: 0
2018-11-18T12:59:23.9386000-00:00 3800 3816 [PortAudio] after paHostApiInitializers[3].
2018-11-18T12:59:23.9386000-00:00 3800 3816 PortAudio initialization successful
2018-11-18T12:59:23.9386000-00:00 3800 3816 Found backend: PortAudio host API index 0 (name: 'MME', type: 2 [MME], default input device: -1, default output device: 1)
2018-11-18T12:59:23.9386000-00:00 3800 3816 Found backend: PortAudio host API index 1 (name: 'Windows DirectSound', type: 1 [DirectSound], default input device: -1, default output device: 2)
2018-11-18T12:59:23.9386000-00:00 3800 3816 Found backend: PortAudio host API index 2 (name: 'Windows WASAPI', type: 13 [WASAPI], default input device: -1, default output device: 4)
2018-11-18T12:59:23.9386000-00:00 3800 3816 Found backend: PortAudio host API index 3 (name: 'Windows WDM-KS', type: 11 [WDMKS], default input device: -1, default output device: -1)
2018-11-18T12:59:23.9386000-00:00 3800 3816 Selecting default PortAudio host API
2018-11-18T12:59:23.9386000-00:00 3800 3816 Selected backend: PortAudio host API index 1 (name: 'Windows DirectSound', type: 1 [DirectSound], default input device: -1, default output device: 2)
2018-11-18T12:59:23.9386000-00:00 3800 3816 Found device: PortAudio device index 0 (name: 'Microsoft Sound Mapper - Output', host API: 0, default sample rate: 44100, max input channels: 0, max output channels: 2, input latency: 0.09 (low) 0.18 (high), output latency: 0.09 (low) 0.18 (high))
2018-11-18T12:59:23.9396000-00:00 3800 3816 Found device: PortAudio device index 1 (name: 'Remote Audio', host API: 0, default sample rate: 44100, max input channels: 0, max output channels: 2, input latency: 0.09 (low) 0.18 (high), output latency: 0.09 (low) 0.18 (high))
2018-11-18T12:59:23.9396000-00:00 3800 3816 Found device: PortAudio device index 2 (name: 'Primary Sound Driver', host API: 1, default sample rate: 44100, max input channels: 0, max output channels: 2, input latency: 0 (low) 0 (high), output latency: 0.12 (low) 0.24 (high))
2018-11-18T12:59:23.9396000-00:00 3800 3816 Found device: PortAudio device index 3 (name: 'Remote Audio', host API: 1, default sample rate: 44100, max input channels: 0, max output channels: 2, input latency: 0 (low) 0 (high), output latency: 0.12 (low) 0.24 (high))
2018-11-18T12:59:23.9396000-00:00 3800 3816 Found device: PortAudio device index 4 (name: 'Remote Audio', host API: 2, default sample rate: 44100, max input channels: 0, max output channels: 2, input latency: 0 (low) 0 (high), output latency: 0.003 (low) 0.05 (high))
2018-11-18T12:59:23.9396000-00:00 3800 3816 Selecting input device
2018-11-18T12:59:23.9396000-00:00 3800 3816 Using default device with index -1
2018-11-18T12:59:23.9396000-00:00 3800 3816 Terminating PortAudio
2018-11-18T12:59:23.9396000-00:00 3800 3816 [PortAudio] TerminateHostApis in
2018-11-18T12:59:23.9396000-00:00 3800 3816 [PortAudio] TerminateHostApis out
2018-11-18T12:59:23.9396000-00:00 3800 3816 PortAudio terminated successfully
2018-11-18T12:59:23.9396000-00:00 3800 3816 Disabling PortAudio debug output redirection
2018-11-18T12:59:23.9396000-00:00 3800 3816 --- EXITING CONTEXT: init() (-999 [ASE_HWMalfunction] Unable to get device info for device index -1)
2018-11-18T12:59:23.9396000-00:00 3800 3816 --- ENTERING CONTEXT: getErrorMessage()
2018-11-18T12:59:23.9396000-00:00 3800 3816 --- EXITING CONTEXT: getErrorMessage() [OK]
2018-11-18T12:59:23.9436000-00:00 3800 3816 Closing logfile

This is not the intended behaviour; FlexASIO should still be able initialize output-only.