Describe what you were doing when the bug occurred:
1. I was using the devtools to investigate some performance issues w/ an app I help maintain
2. I had just turned on the "Record why each component rendered while profiling" checkbox
3. I ran a profile while navigating on the underlying page

The react profiler tab in the devtools gave this error, I think as I clicked the record icon to stop recording the profile.

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DevTools version: 4.5.0-355970aa4

Call stack: at N (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:160881)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:160015)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)
    at j (chrome-extension://fmkadmapgofadopljbjfkapdkoienihi/build/main.js:40:159939)

Component stack: in ec
    in div
    in div
    in div
    in So
    in Unknown
    in n
    in Unknown
    in div
    in div
    in rl
    in Ze
    in fn
    in Ga
    in _s
return 0;
    }
    const existingID = pendingStringTable.get(str);
    if (existingID !== undefined) {
      return existingID;
    }
    const stringID = pendingStringTable.size + 1;
    pendingStringTable.set(str, stringID);
     T
     b
     t
    pendingStringTableLength += str.length + 1;
    return stringID;
  }
  function recordMount(fiber: Fiber, parentFiber: Fiber | null) {
    if (__DEBUG__) {
      debug('recordMount()', fiber, parentFiber);
    }
    const isRoot = fiber.tag === HostRoot;
    const id = getFiberID(getPrimaryFiber(fiber));
    const hasOwnerMetadata = fiber.hasOwnProperty('_debugOwner');
    const isProfilingSupported = fiber.hasOwnProperty('treeBaseDuration');
    if (isRoot) {
      pushOperation(TREE_OPERATION_ADD);
      pushOperation(id);
      pushOperation(ElementTypeRoot);
      pushOperation(isProfilingSupported ? 1 : 0);