Use let instead of var

Author: bob-wilson

Sources/SWBTaskExecution/TaskActions/ClangCompileTaskAction.swift

@@ -249,11 +249,14 @@ public final class ClangCompileTaskAction: TaskAction, BuildValueValidatingTaskA
             }
 
             // Check if verifying dependencies from trace data is enabled.
-            var traceFilePath: Path? = nil
-            var moduleDependenciesContext: ModuleDependenciesContext? = nil
+            let traceFilePath: Path?
+            let moduleDependenciesContext: ModuleDependenciesContext?
             if let payload = task.payload as? ClangTaskPayload {
                 traceFilePath = payload.traceFilePath
                 moduleDependenciesContext = payload.moduleDependenciesContext
+            } else {
+                traceFilePath = nil
+                moduleDependenciesContext = nil
             }
             if let traceFilePath {
                 // Remove the trace output file if it already exists.