[Fix #3182] Make cider-fallback-eval:classpath safer

Basically this should be a no-op if the runtime is not JVM Clojure.

Author: bbatsov

CHANGELOG.md

@@ -5,6 +5,8 @@
 ### Bugs fixed
 
 * [#3195](https://github.com/clojure-emacs/cider/issues/3195): Revert the change that resulted in `(error "Cyclic keymap inheritance")` on `cider-test-run-test`.
+* [#3182](https://github.com/clojure-emacs/cider/issues/3182): Don't try to invoke
+JVM-specific code outside of JVM Clojure.
 
 ## 1.4.0 (2022-05-02)
 

cider-client.el

@@ -593,12 +593,13 @@ Do nothing if PATH is already absolute."
 
 Sometimes the classpath contains entries like src/main and we need to
 resolve those to absolute paths."
-  (let ((classpath (thread-first "(seq (.split (System/getProperty \"java.class.path\") \":\"))"
-                     (cider-sync-tooling-eval)
-                     (nrepl-dict-get "value")
-                     read))
-        (project (clojure-project-dir)))
-    (mapcar (lambda (path) (cider--get-abs-path path project)) classpath)))
+  (when (cider-runtime-clojure-p)
+    (let ((classpath (thread-first "(seq (.split (System/getProperty \"java.class.path\") \":\"))"
+                                   (cider-sync-tooling-eval)
+                                   (nrepl-dict-get "value")
+                                   read))
+          (project (clojure-project-dir)))
+      (mapcar (lambda (path) (cider--get-abs-path path project)) classpath))))
 
 (defun cider-classpath-entries ()
   "Return a list of classpath entries."