Fix StepErrorValidationRule

- Do not report null values
- Include correct error value in diagnostic message
- Use given severity instead of hardcoded warning

server/packages/server-common/src/providers/validation/rules/StepErrorValidationRule.ts

@@ -10,19 +10,21 @@ export class StepExportErrorValidationRule implements ValidationRule {
   public async validate(documentContext: DocumentContext): Promise<Diagnostic[]> {
     const diagnostics: Diagnostic[] = [];
     const steps = documentContext.nodeManager.getStepNodes(true);
-    steps.forEach((step) => {
+    for (const step of steps) {
       const errors = step.properties.find((p) => p.keyNode.value === "errors");
-      if (errors) {
+      if (errors && errors.valueNode && errors.valueNode.type !== "null") {
         const range = documentContext.nodeManager.getNodeRange(errors);
+        const valueRange = documentContext.nodeManager.getNodeRange(errors.valueNode);
+        const errorValue = documentContext.textDocument.getText(valueRange);
         diagnostics.push(
           Diagnostic.create(
             range,
-            `Tool step contains error indicated during Galaxy export - ${errors}`,
-            DiagnosticSeverity.Warning
+            `Tool step contains error indicated during Galaxy export - ${errorValue}`,
+            this.severity
           )
         );
       }
-    });
+    }
     return Promise.resolve(diagnostics);
   }
 }