Debugging crashes under some conditions

[vladimir-kotikov]

We're using this extension in vscode-react-native to debug react-native code running inside separate Node process.

We've found that debuggee process sometimes just crashes after hitting some specific breakpoints with error message, that looks like it's coming somewhere from Node core.

#
# Fatal error in runtime\runtime-debug.cc, line 1423
# Check failed: args[0]->IsJSObject().
#

==== C stack trace ===============================

    v8::Testing::DeoptimizeAll [0x00007FF78E61D346+1835286]
    v8::Testing::DeoptimizeAll [0x00007FF78E7C9EFD+3591373]
    (No symbol) [0x000001C9699063AB]

After some investigation it appeared that the debuggee is actually stops on the breakpoint and reports this event to debugger but right after that, when the extesion tries to request stack, variables, one of these requests causes the crash.

The problem is 100% reproducible using the example at https://github.com/vladimir-kotikov/react_debug_mock/tree/node_v7_crash using the repro steps in README

[weinand]

@vladimir-kotikov this is related to Proxy objects: see microsoft/vscode#12749
Workaround: use the experimental node debugger node2.

[gmramaswamy]

@weinand Can you please help me understand where to specify this debugger "node2". i am using with vscode-react-native extension and in launch.json type is reactnative. please help.

[weinand]

@vladimir-kotikov aha, if your debug type is "reactnative" then you cannot switch to "node2" (and I will move this issue to the vscode-react-native repository).

[weinand]

This issue was moved to microsoft/vscode-react-native#367

[vladimir-kotikov]

@weinand, yep, we're using node debugger under the hood and migrating to node2 is in or backlog.