Fix si_code=, si_addr=undefined. (#14608)

* Fix si_code=, si_addr=undefined.

Author: sean-mcmanus

Extension/src/LanguageServer/extension.ts

@@ -1362,8 +1362,21 @@ async function handleCrashFileRead(crashDirectory: string, crashFile: string, cr
     }
     if (lines[crashStackStartLine].startsWith("SIG")) {
         signalType = `${lines[crashStackStartLine]}\n`;
-        signalInfo = `si_code=${lines[crashStackStartLine + 1]}, si_addr=${bucketSignalAddress(lines[crashStackStartLine + 2])}\n`;
-        crashStackStartLine += 3;
+        const siCodeRaw: string | undefined = lines[crashStackStartLine + 1];
+        const siAddrRaw: string | undefined = lines[crashStackStartLine + 2];
+        const siCode: string = siCodeRaw?.trim() ?? "";
+        const siAddr: string = siAddrRaw?.trim() ?? "";
+        const signalInfoParts: string[] = [];
+        if (siCode.length > 0) {
+            signalInfoParts.push(`si_code=${siCode}`);
+        }
+        if (siAddr.length > 0) {
+            signalInfoParts.push(`si_addr=${bucketSignalAddress(siAddr)}`);
+        }
+        signalInfo = signalInfoParts.length > 0 ? `${signalInfoParts.join(", ")}\n` : "";
+        // Only advance past the header lines that actually exist so a missing si_code/si_addr
+        // line does not cause the first stack frame to be skipped.
+        crashStackStartLine += 1 + (siCodeRaw !== undefined ? 1 : 0) + (siAddrRaw !== undefined ? 1 : 0);
     } else {
         // The signal type may fail to be written.
         // Intentionally different from SIGUNKNOWN from cpptools,