There is a panic when invalid schema of route/operation is used in spec generation. It should prevent it

[marsianin]

When run

swagger generate spec -o swagger.json

i got follow issue

Rinats-MacBook-Pro:gomoona rinat$
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x118 pc=0x1603e4a]

goroutine 1 [running]:
github.com/go-swagger/go-swagger/scan.(*setOpParams).Parse(0xc42e2476e0, 0xc423b9fb00, 0x5, 0x8, 0xc423b9fb00, 0x0)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/route_params.go:109 +0x29a
github.com/go-swagger/go-swagger/scan.(*tagParser).Parse(0xc4205cf310, 0xc423b9fb00, 0x5, 0x8, 0x0, 0xc423b9fb00)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/scanner.go:558 +0x52
github.com/go-swagger/go-swagger/scan.(*sectionedParser).Parse(0xc4205cf9f0, 0xc42e247340, 0xc4205cf620, 0xd)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/scanner.go:944 +0x7f4
github.com/go-swagger/go-swagger/scan.(*routesParser).Parse(0xc43bf5a5c0, 0xc4207fcf80, 0x16fe000, 0xc4277248d0, 0xc42c913d70, 0xc42c913da0, 0x0, 0x0)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/routes.go:110 +0xc55
github.com/go-swagger/go-swagger/scan.(*appScanner).parseRoutes(0xc4304e0d00, 0xc4207fcf80, 0x0, 0x0)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/scanner.go:423 +0xea
github.com/go-swagger/go-swagger/scan.(*appScanner).Parse(0xc4304e0d00, 0xc4304e0d00, 0x0, 0x0)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/scanner.go:351 +0x27b
github.com/go-swagger/go-swagger/scan.Application(0x16c6e1c, 0x1, 0x0, 0x0, 0x16a230f, 0x0, 0x0, 0x0, 0x0, 0x0, ...)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/scan/scanner.go:186 +0x72
github.com/go-swagger/go-swagger/cmd/swagger/commands/generate.(*SpecFile).Execute(0xc420246160, 0xc4200b7f80, 0x0, 0x4, 0xc420246160, 0x1)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/cmd/swagger/commands/generate/spec.go:61 +0x196
github.com/go-swagger/go-swagger/vendor/github.com/jessevdk/go-flags.(*Parser).ParseArgs(0xc420133b00, 0xc4200c0100, 0x4, 0x4, 0x1012518, 0x30, 0xc4200c4900, 0xc420475b00, 0xc420357800)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/vendor/github.com/jessevdk/go-flags/parser.go:316 +0x80b
github.com/go-swagger/go-swagger/vendor/github.com/jessevdk/go-flags.(*Parser).Parse(0xc420133b00, 0x6, 0x179d2fe, 0x6, 0x0, 0x17e8067)
	/Users/rinat/dev/go/src/github.com/go-swagger/go-swagger/vendor/github.com/jessevdk/go-flags/parser.go:186 +0x71

and now:

swagger generate spec -o swagger.json
operation (nightSettings): invalid route schema provided

It was faced by mistaken misprint "swagger:route" when need to use "swagger:operation"

[casualjim]

can you sign off on this PR: https://github.com/go-swagger/go-swagger/pull/1791/checks?check_run_id=30594748

[codecov]

Codecov Report

Merging #1791 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1791      +/-   ##
==========================================
- Coverage   80.04%   80.02%   -0.03%     
==========================================
  Files          38       38              
  Lines        7497     7499       +2     
==========================================
  Hits         6001     6001              
- Misses       1019     1020       +1     
- Partials      477      478       +1

Impacted Files	Coverage Δ
scan/route_params.go	95.08% <0%> (-1.59%)	⬇️

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