fix(rust): prevent overflow in error message calculation

**Problem:** When encountering an invalid symbol at the beginning of the
file, the rust bindings attempt to index the character at position -1 of
the query source, which leads to an overflow and thus invalid character
index which causes a panic.

**Solution:** Bounds check the offset before performing the subtraction.

crates/cli/src/tests/query_test.rs

@@ -342,6 +342,16 @@ fn test_query_errors_on_invalid_symbols() {
                 message: "\"alternatives\"".to_string()
             }
         );
+        assert_eq!(
+            Query::new(&language, "fakefield: (identifier)").unwrap_err(),
+            QueryError {
+                row: 0,
+                offset: 0,
+                column: 0,
+                kind: QueryErrorKind::Field,
+                message: "\"fakefield\"".to_string()
+            }
+        );
     });
 }