fix: Revert that bundle will be appended to body (#1943)

Author: HazAT

packages/browser/src/loader.js

@@ -58,6 +58,7 @@
     // come out in the wrong order. Because of that we don't need async=1 as GA does.
     // it was probably(?) a legacy behavior that they left to not modify few years old snippet
     // https://www.html5rocks.com/en/tutorials/speed/script-loading/
+    var _currentScriptTag = _document.getElementsByTagName(_script)[0];
     var _newScriptTag = _document.createElement(_script);
     _newScriptTag.src = _sdkBundleUrl;
     _newScriptTag.crossorigin = 'anonymous';
@@ -90,9 +91,7 @@
       }
     });
 
-    // We append the script to the body because if you use an `onload` callback it could happen that
-    // the `onLoad` of the already injected SDK will be called, which breaks the setup flow.
-    document.body.appendChild(_newScriptTag);
+    _currentScriptTag.parentNode.insertBefore(_newScriptTag, _currentScriptTag);
   }
 
   function sdkLoaded(callbacks, SDK) {
@@ -107,8 +106,9 @@
       }
 
       var initAlreadyCalled = false;
+      var __sentry = _window['__SENTRY__'];
       // If there is a global __SENTRY__ that means that in any of the callbacks init() was already invoked
-      if (!(typeof _window['__SENTRY__'] === 'undefined')) {
+      if (!(typeof __sentry === 'undefined') && __sentry.hub && __sentry.hub.getClient()) {
         initAlreadyCalled = true;
       }