MetaMaskOnboarding

At line 184 `isMetamaskInstalled()` will return `undefined` so turning it into a false positive will go for Onboarding

```
const updateButtons = () => {
const accountButtonsDisabled = !isMetaMaskInstalled() || !isMetaMaskConnected()
if (accountButtonsDisabled) {
for (const button of accountButtons) {
button.disabled = true
}
clearTextDisplays()
} else {
deployButton.disabled = false
sendButton.disabled = false
createToken.disabled = false
personalSign.disabled = false
signTypedData.disabled = false
getEncryptionKeyButton.disabled = false
ethSign.disabled = false
personalSign.disabled = false
signTypedData.disabled = false
signTypedDataV3.disabled = false
signTypedDataV4.disabled = false
}

if (!isMetaMaskInstalled()) {
addEthereumChain.disabled = true
onboardButton.innerText = 'Click here to install MetaMask!'
onboardButton.onclick = onClickInstall
onboardButton.disabled = false
} else if (isMetaMaskConnected()) {
addEthereumChain.disabled = false
onboardButton.innerText = 'Connected'
onboardButton.disabled = true
if (onboarding) {
onboarding.stopOnboarding()
}
} else {
addEthereumChain.disabled = true
onboardButton.innerText = 'Connect'
onboardButton.onclick = onClickConnect
onboardButton.disabled = false
}
}
```

Start at line 184 and inspect isMetaMaskInstalled() together with updateButtons and its onboarding branches. Verify the undefined result follows the intended not-installed path, showing the install prompt rather than the connected state, and confirm the account buttons remain disabled.

Written by the indexing model from the issue text.