fix: nil error SEGFAULT (#42)

* fix: nil error SEGFAULT

Also, improves error message readability for unknown request

* chore: Address Copilot feedback

* Update notecard/validate.go

Notecard API is case sensitive

Author: zfields

.vscode/launch.json

@@ -0,0 +1,35 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "inputs": [
+        {
+            "id": "requestJson",
+            "type": "promptString",
+            "description": "Enter the JSON request string for the CLI",
+            "default": "{\"req\":\"card.attn\",\"mode\":\"watchdog\",\"seconds\":30}"
+        }
+    ],
+    "configurations": [
+        {
+            "name": "Launch Notecard CLI",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${workspaceFolder}/notecard",
+            "args": ["-req", "${input:requestJson}"],
+            "env": {
+                "BLUES": "[email protected]"
+            }
+        },
+        {
+            "name": "Launch Notehub CLI",
+            "type": "go",
+            "request": "launch",
+            "mode": "auto",
+            "program": "${workspaceFolder}/notehub",
+            "args": ["-req", "${input:requestJson}"]
+        }
+    ]
+}

notecard/validate.go

@@ -81,6 +81,12 @@ func fetchAndCacheSchema(url string, verbose bool) (io.Reader, error) {
 }
 
 func formatErrorMessage(reqType string, errUnformatted error) (err error) {
+	// Check if the error is nil
+	if errUnformatted == nil {
+		return nil
+	}
+
+	// Convert the error to a string
 	errMsg := errUnformatted.Error()
 
 	// Define constants
@@ -230,15 +236,22 @@ func resolveSchemaError(reqMap map[string]interface{}, verbose bool) (err error)
 	} else if reqTypeStr == "" {
 		err = fmt.Errorf("no request type specified")
 	} else {
-		var reqSchema *jsonschema.Schema
-		reqSchema, err = jsonschema.Compile(filepath.Join(cacheDir, reqTypeStr+".req.notecard.api.json"))
-		if err == nil {
-			err = reqSchema.Validate(reqMap)
-			if !verbose {
-				err = formatErrorMessage(reqTypeStr, err)
+		// Validate against the specific request schema
+		schemaPath := filepath.Join(cacheDir, reqTypeStr+".req.notecard.api.json")
+		if _, err = os.Stat(schemaPath); os.IsNotExist(err) {
+			err = fmt.Errorf("unknown request type: %s", reqTypeStr)
+		} else if err == nil {
+			var reqSchema *jsonschema.Schema
+			reqSchema, err = jsonschema.Compile(schemaPath)
+			if err == nil {
+				err = reqSchema.Validate(reqMap)
+				if err != nil && !verbose {
+					err = formatErrorMessage(reqTypeStr, err)
+				}
 			}
 		}
 	}
+
 	return err
 }