Apply suggestions from code review

Co-authored-by: Alon Zakai <azakai@google.com>
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 8db334f..d486ef1 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -511,7 +511,7 @@
     size_t offset = parseIndex(s);
     if (offset >= tableNames.size()) {
       throw ParseException(
-        "unknown table in getTableName"s + s.toString(), s.line, s.col);
+        "unknown table in getTableName: "s + s.toString(), s.line, s.col);
     }
     return tableNames[offset];
   }
@@ -525,7 +525,7 @@
     size_t offset = parseIndex(s);
     if (offset >= elemSegmentNames.size()) {
       throw ParseException(
-        "unknown elem segment"s + s.toString(), s.line, s.col);
+        "unknown elem segment: "s + s.toString(), s.line, s.col);
     }
     return elemSegmentNames[offset];
   }