Fix ido-ubiquitous-debug-mode messages

All fallbacks were previously being reported as unknown errors due to
unintended redundant wrapping of all fallback signals inside another
fallback signal. Also, now the second argument to signal is always a
list, as the documentation says.

ido-cr+-debug-mode messages also got the equivalent treatment.

ido-completing-read+.el

@@ -143,9 +143,9 @@ https://github.com/DarwinAwardWinner/ido-ubiquitous/issues"
   (when ido-cr+-debug-mode
     (when (and (listp arg)
                (eq (car arg) 'ido-cr+-fallback))
-      (setq arg (cdr arg)))
+      (setq arg (cadr arg)))
     (ido-cr+--debug-message "Falling back to `%s' because %s."
-                                   ido-cr+-fallback-function arg)))
+                            ido-cr+-fallback-function arg)))
 
 ;;;###autoload
 (defun ido-completing-read+ (prompt collection &optional predicate
@@ -169,22 +169,23 @@ completion for them."
           (cond
            (inherit-input-method
             (signal 'ido-cr+-fallback
-                    "ido cannot handle non-nil INHERIT-INPUT-METHOD"))
+                    '("ido cannot handle non-nil INHERIT-INPUT-METHOD")))
            ((bound-and-true-p completion-extra-properties)
             (signal 'ido-cr+-fallback
-                    "ido cannot handle non-nil `completion-extra-properties'"))
+                    '("ido cannot handle non-nil `completion-extra-properties'")))
            ((functionp collection)
             (signal 'ido-cr+-fallback
-                    "ido cannot handle COLLECTION being a function")))
+                    '("ido cannot handle COLLECTION being a function"))))
           ;; Expand all possible completions
           (setq collection (all-completions "" collection predicate))
           ;; Check for excessively large collection
           (when (and ido-cr+-max-items
                      (> (length collection) ido-cr+-max-items))
             (signal 'ido-cr+-fallback
-                    (format
-                     "there are more than %i items in COLLECTION (see `ido-cr+-max-items')"
-                     ido-cr+-max-items)))
+                    (list
+                     (format
+                      "there are more than %i items in COLLECTION (see `ido-cr+-max-items')"
+                      ido-cr+-max-items))))
           ;; ido doesn't natively handle DEF being a list. If DEF is a
           ;; list, prepend it to COLLECTION and set DEF to just the
           ;; car of the default list.
@@ -219,7 +220,7 @@ completion for them."
             ;; This detects when the user triggered fallback mode
             ;; manually.
             (when (eq ido-exit 'fallback)
-              (signal 'ido-cr+-fallback "user manually triggered fallback"))))
+              (signal 'ido-cr+-fallback '("user manually triggered fallback")))))
       ;; Handler for ido-cr+-fallback signal
       (ido-cr+-fallback
        (ido-cr+--explain-fallback sig)

ido-ubiquitous.el

@@ -114,7 +114,7 @@ Debug info is printed to the *Messages* buffer."
   (when ido-ubiquitous-debug-mode
     (when (and (listp arg)
                (eq (car arg) 'ido-ubiquitous-fallback))
-      (setq arg (cdr arg)))
+      (setq arg (cadr arg)))
     (ido-ubiquitous--debug-message "Falling back to `%s' because %s."
                                    ido-cr+-fallback-function arg)))
 
@@ -667,7 +667,7 @@ completion for them."
               ;; If ido-ubiquitous is disabled this time, fall back
               (when (eq ido-ubiquitous-active-state 'disable)
                 (signal 'ido-ubiquitous-fallback
-                        "`ido-ubiquitous-active-state' is `disable'"))
+                        '("`ido-ubiquitous-active-state' is `disable'")))
               ;; Handle a collection that is a function: either expand
               ;; completion list now or fall back
               (when (functionp collection)
@@ -679,15 +679,20 @@ completion for them."
                           ;; so it now becomes redundant.
                           predicate nil)
                   (signal 'ido-ubiquitous-fallback
-                          "COLLECTION is a function and there is no override")))
+                          '("COLLECTION is a function and there is no override"))))
               (let ((ido-ubiquitous-enable-next-call t))
                 (ido-completing-read+
                  prompt collection predicate require-match
                  initial-input hist def inherit-input-method)))
+          ;; Pass through any known fallback signals to the outer
+          ;; `condition-case'
+          (ido-ubiquitous-fallback
+           (signal (car err) (cdr err)))
+          ;; Convert any other error into a fallback signal.
           (error
            (signal 'ido-ubiquitous-fallback
-                   (format "ido-ubiquitous encountered an unexpected error: %S"
-                           err))))
+                   (list (format "ido-ubiquitous encountered an unexpected error: %S"
+                                 err)))))
       ;; Handler for ido-ubiquitous-fallback signal
       (ido-ubiquitous-fallback
        (ido-ubiquitous--explain-fallback sig)