Correct Makefile check extenstions

Makefile

@@ -1,5 +1,7 @@
 # Makefile for Jan Electron App - Build, Lint, Test, and Clean
 
+.SHELLFLAGS := -eu -o pipefail -c
+
 # Default target, does nothing
 all:
 	@echo "Specify a target to run"
@@ -21,19 +23,11 @@ endif
 	yarn install
 	yarn build:extensions
 
-#
 check-file-counts: install-and-build
 ifeq ($(OS),Windows_NT)
 	powershell -Command "$$tgz_count = (Get-ChildItem -Path electron/pre-install -Filter *.tgz | Measure-Object | Select-Object -ExpandProperty Count); $$dir_count = (Get-ChildItem -Path extensions -Directory | Measure-Object | Select-Object -ExpandProperty Count); if ($$tgz_count -ne $$dir_count) { Write-Host 'Number of .tgz files in electron/pre-install (' + $$tgz_count + ') does not match the number of subdirectories in extension (' + $$dir_count + ')'; exit 1 } else { Write-Host 'Extension build successful' }"
 else
-	@tgz_count=$$(find electron/pre-install -name "*.tgz" | wc -l); \
-	dir_count=$$(find extension -mindepth 1 -maxdepth 1 -type d | wc -l); \
-	if [ $$tgz_count -ne $$dir_count ]; then \
-		echo "Number of .tgz files in 'electron/pre-install' ($$tgz_count) does not match the number of subdirectories in 'extension' ($$dir_count)"; \
-		exit 1; \
-	else
-		echo "Extension build successful";
-	fi
+	@tgz_count=$$(find electron/pre-install -type f -name "*.tgz" | wc -l); dir_count=$$(find extensions -mindepth 1 -maxdepth 1 -type d | wc -l); if [ $$tgz_count -ne $$dir_count ]; then echo "Number of .tgz files in electron/pre-install ($$tgz_count) does not match the number of subdirectories in extension ($$dir_count)"; exit 1; else echo "Extension build successful"; fi
 endif
 
 dev: check-file-counts