A former exec at X, previously Twitter, says Elon Musk was at times more impulsive than she expected.
• Ella Irwin told NBC News there was "more emotion behind his decisions" than she anticipated.
• Musk's biographer has noted he has a "dark streak." Musk's ex, Grimes, calls it "demon mode."
A former exec at X, previously known as Twitter, says there was at least one element…