various typing fixes (#15899)

* add blspy-stubs to improve mypy

* various typing fixes

* avoid cast

* use ValueError exception instead of assert when aborting picking a wallet key

install.sh

@@ -20,6 +20,7 @@ usage() {
 
 PACMAN_AUTOMATED=
 EXTRAS=
+BLSPY_STUBS=
 SKIP_PACKAGE_INSTALL=
 PLOTTER_INSTALL=
 EDITABLE='-e'
@@ -30,7 +31,7 @@ do
     # automated
     a) PACMAN_AUTOMATED=--noconfirm;;
     # development
-    d) EXTRAS=${EXTRAS}dev,;;
+    d) EXTRAS=${EXTRAS}dev,;BLSPY_STUBS=1;;
     # non-editable
     i) EDITABLE='';;
     # legacy keyring
@@ -334,6 +335,10 @@ python -m pip install wheel
 python -m pip install --extra-index-url https://pypi.chia.net/simple/ miniupnpc==2.2.2
 python -m pip install ${EDITABLE} ."${EXTRAS}" --extra-index-url https://pypi.chia.net/simple/
 
+if [ -n "$BLSPY_STUBS" ]; then
+python -m pip install ${EDITABLE} ./blspy-stubs
+fi
+
 if [ -n "$PLOTTER_INSTALL" ]; then
   set +e
   PREV_VENV="$VIRTUAL_ENV"