Watch mode breaks when adding new files

[plt-amy]

Adding a new file while watch mode is running leaves me in a loop of

🔨 src/Cat/Displayed/Cartesian/Indexing.lagda.md has changed. Rebuilding _build/html/Cat.Displayed.Cartesian.Indexing.html.
# agda (for OracleQ (MainCompileQ ()))
Checking Cat.Displayed.Cartesian.Indexing (/home/amelia/default/Projects/1lab.dev/src/Cat/Displayed/Cartesian/Indexing.lagda.md).
Generating HTML for Cat.Displayed.Cartesian.Indexing
❌ Build failed in 1.68s
Error when running Shake build system:
  at need, called at app/Main.hs:276:22 in main:Main
* Depends on: _build/html/Cat.Displayed.Cartesian.Indexing.html
  at copyFile', called at app/Main.hs:95:12 in main:Main
  at need, called at src/Development/Shake/Internal/Derived.hs:92:5 in shake-0.19.6-7wpTzbc7Oxe2G9GkWOH0sV:Development.Shake.Internal.Derived
* Depends on: _build/html0/Cat.Displayed.Cartesian.Indexing.html
  at error, called at src/Development/Shake/Internal/Rules/File.hs:179:58 in shake-0.19.6-7wpTzbc7Oxe2G9GkWOH0sV:Development.Shake.Internal.Rules.File
* Raised the exception:
Error, rule finished running but did not produce file:
  _build/html0/Cat.Displayed.Cartesian.Indexing.html