fix null pointer access in unused.d

Author: WebFreak001

src/dscanner/analysis/unused.d

@@ -434,7 +434,8 @@ abstract class UnusedStorageCheck : UnusedIdentifierCheck
 		// enum name = "abc";
 		// __traits(hasMember, S, name);
 		ignoreDeclarations++;
-		traitsExp.templateArgumentList.accept(this);
+		if (traitsExp.templateArgumentList)
+			traitsExp.templateArgumentList.accept(this);
 		ignoreDeclarations--;
 	}
 

src/dscanner/analysis/unused_variable.d

@@ -117,6 +117,12 @@ final class UnusedVariableCheck : UnusedStorageCheck
 		__traits(compiles, { int i = 2; });
 	}
 
+	// segfault with null templateArgumentList
+	void nullTest()
+	{
+		__traits(isPOD);
+	}
+
 	}c, sac);
 	stderr.writeln("Unittest for UnusedVariableCheck passed.");
 }