Remove type checks from slash-checking functions

addon/ajax-request.js

@@ -43,30 +43,22 @@ function isJSONAPIContentType(header) {
 }
 
 function startsWithSlash(string) {
-  if (typeof string === 'string') {
-    return string.charAt(0) === '/';
-  }
-  return string;
+  return string.charAt(0) === '/';
 }
 
 function endsWithSlash(string) {
-  if (typeof string === 'string') {
-    return string.charAt(string.length - 1) === '/';
-  }
-  return string;
+  return string.charAt(string.length - 1) === '/';
 }
 
 function stripSlashes(path) {
-  if (typeof path === 'string') {
-    // make sure path starts with `/`
-    if (startsWithSlash(path)) {
-      path = path.substring(1);
-    }
+  // make sure path starts with `/`
+  if (startsWithSlash(path)) {
+    path = path.substring(1);
+  }
 
-    // remove end `/`
-    if (endsWithSlash(path)) {
-      path = path.slice(0, -1);
-    }
+  // remove end `/`
+  if (endsWithSlash(path)) {
+    path = path.slice(0, -1);
   }
   return path;
 }
@@ -279,7 +271,10 @@ export default class AjaxRequest {
     }
 
     const host = options.host || get(this, 'host');
-    const namespace = stripSlashes(get(this, 'namespace'));
+    let namespace = get(this, 'namespace');
+    if (namespace) {
+      namespace = stripSlashes(namespace);
+    }
 
     let fullUrl = '';
     // Add the host, if it exists