Fix exception capture tests failing in Release configuration

In Release builds, JIT optimizations strip source file paths from
async state machine stack frames, causing assertions on filename and
context_line to fail. Guard these assertions on whether source info
is actually present, and skip the IO-lock test when no source path
is available.

Author: haacked

tests/UnitTests/PostHogClientTests.cs

@@ -936,12 +936,21 @@ public async Task CaptureExceptionWithDivideByZeroException() // based on PostHo
 
             var frames = GetStackFrames(firstException);
             Assert.NotEmpty(frames);
-            Assert.Contains(frames, f =>
+
+            // Source file paths and context lines may be absent in Release builds
+            // due to JIT optimizations stripping debug info from async state machines.
+            var hasSourceInfo = frames.Any(f =>
                 f.TryGetProperty("filename", out var fn) &&
-                fn.GetString()!.EndsWith(".cs", StringComparison.OrdinalIgnoreCase));
-            Assert.Contains(frames, f =>
-                f.TryGetProperty("context_line", out var cl) &&
-                cl.GetString()!.Contains("var result = 1 / zero;", StringComparison.OrdinalIgnoreCase));
+                !string.IsNullOrEmpty(fn.GetString()));
+            if (hasSourceInfo)
+            {
+                Assert.Contains(frames, f =>
+                    f.TryGetProperty("filename", out var fn) &&
+                    fn.GetString()!.EndsWith(".cs", StringComparison.OrdinalIgnoreCase));
+                Assert.Contains(frames, f =>
+                    f.TryGetProperty("context_line", out var cl) &&
+                    cl.GetString()!.Contains("var result = 1 / zero;", StringComparison.OrdinalIgnoreCase));
+            }
 
             Assert.Equal("2024-01-21T19:08:23+00:00", batchItem.GetProperty("timestamp").GetString());
         }
@@ -1010,9 +1019,15 @@ public async Task CaptureExceptionWithAggregateException()
                 f.TryGetProperty("filename", out var fn) &&
                 string.IsNullOrEmpty(fn.GetString()));
 
-            Assert.Contains(frames, f =>
-                f.TryGetProperty("context_line", out var cl) &&
-                cl.GetString()!.Contains("var invalid = list[5];", StringComparison.OrdinalIgnoreCase));
+            var hasSourceInfo = frames.Any(f =>
+                f.TryGetProperty("filename", out var fn) &&
+                !string.IsNullOrEmpty(fn.GetString()));
+            if (hasSourceInfo)
+            {
+                Assert.Contains(frames, f =>
+                    f.TryGetProperty("context_line", out var cl) &&
+                    cl.GetString()!.Contains("var invalid = list[5];", StringComparison.OrdinalIgnoreCase));
+            }
         }
     }
 
@@ -1103,9 +1118,16 @@ public async Task CaptureExceptionCauseIOFailureEmptyContext()
                     .Select(f => f?.GetFileName())
                     .FirstOrDefault(p => !string.IsNullOrEmpty(p) && File.Exists(p));
 
+                // In Release builds, stack frames may not include source file paths due
+                // to JIT optimizations, making this scenario impossible to reproduce.
+                if (path is null)
+                {
+                    return;
+                }
+
                 // Lock the source file exclusively so File.ReadAllLines(path) will throw IOException
                 // and as result frames will not contain source code context
-                lockHandle = new FileStream(path!, FileMode.Open, FileAccess.Read, FileShare.None);
+                lockHandle = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None);
 
                 client.CaptureException(ex, "some-distinct-id");
                 await client.FlushAsync();
@@ -1115,7 +1137,7 @@ public async Task CaptureExceptionCauseIOFailureEmptyContext()
                 var divideByZeroException = GetExceptionOfType(props, "System.DivideByZeroException");
                 var frames = GetStackFrames(divideByZeroException);
 
-                Assert.True(File.Exists(path!));
+                Assert.True(File.Exists(path));
                 Assert.Equal("$exception", batchItem.GetProperty("event").GetString());
                 AssertContextEmpty(frames[0]);
             }