[wasm][debugger] NRE seen in proxy when loading symbols from symbol server

[radical]

I saw this in https://dev.azure.com/dnceng-public/public/_build/results?buildId=355827&view=logs&j=1567862a-6a9e-5016-9353-cc84f1411dc4&t=95224710-367f-55b7-6b5e-1fa98616b1e8 which is on an unrelated #88929 .

From the proxy log:

[ERR] DevToolsProxy-15: Failed to load symbols from symbol server. (Object reference not set to an instance of an object.)
[VRB] DevToolsProxy-15: SymbolChecksum: SHA256:35ddd68863cd8cde7a42eb5a29c56074321f4b909d6738bc80d64f7aeb466c72
[ERR] DevToolsProxy-15: Failed to load symbols from symbol server. (A task was canceled.)

The tests also timed out. The proxy shows tests running for a roughly ~2mins in total.

cc @thaystg

Tagging subscribers to 'arch-wasm': @lewing
See info in area-owners.md if you want to be subscribed.

Issue Details

---

I saw this in https://dev.azure.com/dnceng-public/public/_build/results?buildId=355827&view=logs&j=1567862a-6a9e-5016-9353-cc84f1411dc4&t=95224710-367f-55b7-6b5e-1fa98616b1e8 which is on an unrelated #88929 .

From the proxy log:

[ERR] DevToolsProxy-15: Failed to load symbols from symbol server. (Object reference not set to an instance of an object.)
[VRB] DevToolsProxy-15: SymbolChecksum: SHA256:35ddd68863cd8cde7a42eb5a29c56074321f4b909d6738bc80d64f7aeb466c72
[ERR] DevToolsProxy-15: Failed to load symbols from symbol server. (A task was canceled.)

The tests also timed out. The proxy shows tests running for a roughly ~2mins in total.

cc @thaystg

Author:	radical
Assignees:	-
Labels:	arch-wasm, area-Debugger-mono
Milestone:	8.0.0

[lewing]

This is likely a network error, what is the frequency?

[radical]

This is likely a network error, what is the frequency?

No idea really. This is from the proxy log, so this was found only when grep'ing the proxy log.

note to self: log the trace as a debug message.

[radical]

This was hit again (build and log):

[xUnit.net 00:02:04.49]     DebuggerTests.SteppingTests.SteppingIntoLibrarySymbolsLoadedFromSymbolServerRemoveSymbolServerAndStepAgain(secondServers: []) [FAIL]
  Failed DebuggerTests.SteppingTests.SteppingIntoLibrarySymbolsLoadedFromSymbolServerRemoveSymbolServerAndStepAgain(secondServers: []) [57 s]
  Error Message:
   System.Threading.Tasks.TaskCanceledException : A task was canceled.
  Stack Trace:
     at DebuggerTests.DebuggerTestBase.SendCommandAndCheck(JObject args, String method, String script_loc, Int32 line, Int32 column, String function_name, Func`2 wait_for_event_fn, Func`2 locals_fn, String waitForEvent) in /_/src/mono/wasm/debugger/DebuggerTestSuite/DebuggerTestBase.cs:line 674
   at DebuggerTests.DebuggerTestBase.StepAndCheck(StepKind kind, String script_loc, Int32 line, Int32 column, String function_name, Func`2 wait_for_event_fn, Func`2 locals_fn, Int32 times) in /_/src/mono/wasm/debugger/DebuggerTestSuite/DebuggerTestBase.cs:line 629
   at DebuggerTests.SteppingTests.SteppingIntoLibrarySymbolsLoadedFromSymbolServerRemoveSymbolServerAndStepAgain(String[] secondServers) in /_/src/mono/wasm/debugger/DebuggerTestSuite/SteppingTests.cs:line 1196
--- End of stack trace from previous location ---
  Standard Output Messages:
 | [2023-08-20T21:04:18] DevToolsProxy-13 Error: Failed to load symbols from symbol server. (The operation was canceled.)
 | [2023-08-20T21:04:18] DevToolsProxy-13 Error: Failed to load symbols from symbol server. (Object reference not set to an instance of an object.)
 | [2023-08-20T21:04:18] DevToolsProxy-13 Error: Failed to load symbols from symbol server. (Object reference not set to an instance of an object.)
 | [2023-08-20T21:04:18] DevToolsProxy-13 Error: Failed to load symbols from symbol server. (Object reference not set to an instance of an object.)