fix missing checks

Author: charles-zablit

lldb/source/Plugins/Language/Swift/SwiftLanguage.cpp

@@ -1952,6 +1952,11 @@ GetDemangledFunctionPrefix(const SymbolContext &sc) {
 
   auto [demangled_name, info] = *info_or_err;
 
+  if (!info.hasPrefix())
+    return llvm::createStringError(
+        "DemangledInfo for '%s does not have suffix range.",
+        demangled_name.data());
+
   return demangled_name.slice(info.PrefixRange.first, info.PrefixRange.second);
 }
 
@@ -1963,6 +1968,11 @@ GetDemangledFunctionSuffix(const SymbolContext &sc) {
 
   auto [demangled_name, info] = *info_or_err;
 
+  if (!info.hasSuffix())
+    return llvm::createStringError(
+        "DemangledInfo for '%s does not have suffix range.",
+        demangled_name.data());
+
   return demangled_name.slice(info.SuffixRange.first, info.SuffixRange.second);
 }
 
@@ -1971,9 +1981,9 @@ static bool PrintDemangledArgumentList(Stream &s, const SymbolContext &sc) {
 
   auto info_or_err = GetAndValidateInfo(sc);
   if (!info_or_err) {
-    LLDB_LOG_ERROR(
-        GetLog(LLDBLog::Language), info_or_err.takeError(),
-        "Failed to handle ${{function.basename}} frame-format variable: {0}");
+    LLDB_LOG_ERROR(GetLog(LLDBLog::Language), info_or_err.takeError(),
+                   "Failed to handle ${{function.formatted-arguments}} "
+                   "frame-format variable: {0}");
     return false;
   }
   auto [demangled_name, info] = *info_or_err;