Default inline errors/warnings to on in the backend

Author: Brian Vaughn

packages/react-devtools-shared/src/backend/renderer.js

@@ -634,7 +634,7 @@ export function attach(
     const breakOnConsoleErrors =
       window.__REACT_DEVTOOLS_BREAK_ON_CONSOLE_ERRORS__ === true;
     const showInlineWarningsAndErrors =
-      window.__REACT_DEVTOOLS_SHOW_INLINE_WARNINGS_AND_ERRORS__ === true;
+      window.__REACT_DEVTOOLS_SHOW_INLINE_WARNINGS_AND_ERRORS__ !== false;
     if (appendComponentStack || breakOnConsoleErrors) {
       patchConsole({
         appendComponentStack,

packages/react-devtools-shared/src/hook.js

@@ -183,7 +183,7 @@ export function installHook(target: any): DevToolsHook | null {
         const breakOnConsoleErrors =
           window.__REACT_DEVTOOLS_BREAK_ON_CONSOLE_ERRORS__ === true;
         const showInlineWarningsAndErrors =
-          window.__REACT_DEVTOOLS_SHOW_INLINE_WARNINGS_AND_ERRORS__ === true;
+          window.__REACT_DEVTOOLS_SHOW_INLINE_WARNINGS_AND_ERRORS__ !== false;
 
         // The installHook() function is injected by being stringified in the browser,
         // so imports outside of this function do not get included.