Fixes #4 Improve error reporting

src/GithubError.ts

@@ -0,0 +1,61 @@
+export class GithubError {
+    error: any;
+
+    constructor(error: any) {
+        this.error = error
+    }
+
+    toString(): string {
+        const code = this.error.code 
+        switch(code) {
+            case 'missing':
+                return this.missingResourceMessage()
+            case 'missing_field':
+                return this.missingFieldMessage()
+            case 'invalid':
+                return this.invalidFieldMessage()
+            case 'already_exists':
+                return this.resourceAlreadyExists()
+            default:
+                return this.customErrorMessage()
+        }
+    }
+
+    private customErrorMessage(): string {
+        const message = this.error.message;
+        const documentation = this.error.documentation_url
+
+        let documentationMessage: string
+        if(documentation) {
+            documentationMessage = `\nPlease see ${documentation}.`
+        } else {
+            documentationMessage = ""
+        }
+
+        return `${message}${documentationMessage}`
+    }
+
+    private invalidFieldMessage(): string {
+        const resource = this.error.resource
+        const field = this.error.field
+
+        return `The ${field} field on ${resource} is an invalid format.`
+    }
+    
+    private missingResourceMessage(): string {
+        const resource = this.error.resource
+        return `${resource} does not exist.`
+    }
+
+    private missingFieldMessage(): string {
+        const resource = this.error.resource
+        const field = this.error.field
+
+        return `The ${field} field on ${resource} is missing.`
+    }
+
+    private resourceAlreadyExists(): string {
+        const resource = this.error.resource
+        return `${resource} already exists.`
+    }
+}