LSIF tool has uncaught exception when Uri is relative path

[noellelc]

Version Used: 4.0.0-3.21372.2

Steps to Reproduce:

1. Run LSIF tool on certain projects
2. Tool succeeds across several documents within a project
3. Tool throws an unhandled exception:

Unhandled exception: System.AggregateException: One or more errors occurred. ---> System.InvalidOperationException: This operation is not supported for a relative URI.
  at System.Uri.get_AbsoluteUri()
  at Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Writing.LsifConverter.WriteJson(JsonWriter writer, Object value, JsonSerializer serializer) in /_/src/Features/Lsif/Generator/Writing/LsifConverter.cs:line 33
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeConvertable(JsonWriter writer, JsonConverter converter, Object value, JsonContract contract, JsonContainerContract collectionContract, JsonProperty containerProperty)
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
  at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
  at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
  at Newtonsoft.Json.JsonConvert.SerializeObjectInternal(Object value, Type type, JsonSerializer jsonSerializer)
  at Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Writing.LineModeLsifJsonWriter.WriteAll(List`1 elements) in /_/src/Features/Lsif/Generator/Writing/LineModeLsifJsonWriter.cs:line 49
  at Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Writing.BatchingLsifJsonWriter.FlushToUnderlyingAndEmpty() in /_/src/Features/Lsif/Generator/Writing/BatchingLsifJsonWriter.cs:line 80
  at Microsoft.CodeAnalysis.LanguageServerIndexFormat.Generator.Generator.<>c__DisplayClass12_0.<GenerateForCompilation>b__0(SyntaxTree syntaxTree) in /_/src/Features/Lsif/Generator/Generator.cs:line 89
  at System.Threading.Tasks.Parallel.<>c__DisplayClass17_0`1.<ForWorker>b__1()
  at System.Threading.Tasks.Task.InnerInvokeWithArg(Task childTask)
  at System.Threading.Tasks.Task.<>c__DisplayClass176_0.<ExecuteSelfReplicating>b__0(Object )

Expected Behavior:
Tool still runs sucessfully if document uris are relative paths.

Actual Behavior:
I'm not sure if this is the root cause, but it appears at this point in the Generator tool, a relative or absolute uri is expected for document, but here, an absolute uri is expected but uncaught if the uri is not absolute.

[jasonmalinowski]

@noellelc Hmm, so for source generated files where we don't have a full path, what would you like us to do? I can do file://<relative path> but not sure if you want us to do something else there?

[tmat]

#51998 and #51773.

[noellelc]

It looks like in your PR @jasonmalinowski you're just going to leave it as a relative path, which works for us!

[jasonmalinowski]

@noellelc All right, we'll go with that for now!

[jasonmalinowski]

@noellelc And I guess to clarify it's just a relative path. Not even a file:// prefix; that OK?

[noellelc]

Yes--we have checks that allow for a relative uri. Thanks!