Removed circular dependencies between APIs and CMI objects

No longer directly setting error codes on the API when a read/write or data validation fails, throwing exceptions instead that can then be caught by the APi.

src/exceptions.js

@@ -0,0 +1,33 @@
+// @flow
+
+/**
+ * Data Validation Exception
+ */
+export class ValidationError extends Error {
+  /**
+   * Constructor to take in an error message and code
+   * @param {number} errorCode
+   */
+  constructor(errorCode: number) {
+    super(errorCode);
+    this.#errorCode = errorCode;
+  }
+
+  #errorCode;
+
+  /**
+   * Getter for #errorCode
+   * @return {number}
+   */
+  get errorCode() {
+    return this.#errorCode;
+  }
+
+  /**
+   * Trying to override the default Error message
+   * @return {string}
+   */
+  get message() {
+    return this.#errorCode + '';
+  }
+}