Refactored to typescript & more consistent code

Updated how we interface with figlet and unified error handling &
response.

src/errors.ts

@@ -0,0 +1,47 @@
+class MissingTextError extends Error {
+  error: string
+  statusCode: number
+
+  constructor(error = null) {
+    const message = `Missing query parameter 'text'.`;
+    super(message);
+
+    this.error = error;
+    this.statusCode = 400;
+  }
+}
+
+class FontNotFoundError extends Error {
+  error: string
+  statusCode: number
+
+  constructor(font, error = null) {
+    const message = `Font '${font}' not found. Check /fonts.`;
+    super(message);
+
+    this.error = error;
+    this.statusCode = 404;
+  }
+}
+
+class UnexpectedFigletError extends Error {
+  error: string
+  statusCode: number
+
+  constructor(error) {
+    const message = "Unexpected error from figlet!"
+    super(message)
+
+    this.error = error;
+    this.statusCode = 500
+
+    console.log(message)
+    console.log(error)
+  }
+}
+
+export {
+  MissingTextError,
+  FontNotFoundError,
+  UnexpectedFigletError
+};