import: Properly report "no specific version" errors.

* guix/import/cpan.scm (latest-release): Use 'raise' instead of
'error'.
* guix/import/elpa.scm (latest-release): Likewise.
* guix/import/hackage.scm (latest-release): Likewise.
* guix/import/minetest.scm (latest-minetest-release): Likewise.
* guix/import/opam.scm (latest-release): Likewise.
* guix/import/stackage.scm (latest-lts-release): Likewise.

guix/import/cpan.scm

@@ -28,6 +28,7 @@
   #:use-module ((ice-9 rdelim) #:select (read-line))
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
   #:use-module (json)
   #:use-module (gcrypt hash)
   #:use-module (guix diagnostics)
@@ -310,7 +311,7 @@ in RELEASE, a <cpan-release> record."
 (define* (latest-release package #:key (version #f))
   "Return an <upstream-source> for the latest release of PACKAGE."
   (when version
-    (error
+    (raise
      (formatted-message
       (G_ "~a updater doesn't support updating to a specific version, sorry.")
       "cpan")))

guix/import/elpa.scm

@@ -34,6 +34,7 @@
   #:use-module (srfi srfi-9 gnu)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-35)
   #:use-module (guix i18n)
   #:use-module (guix diagnostics)
@@ -405,7 +406,7 @@ type '<elpa-package>'."
   (define repo (elpa-repository package))
 
   (when version
-    (error
+    (raise
      (formatted-message
       (G_ "~a updater doesn't support updating to a specific version, sorry.")
       "elpa")))

guix/import/hackage.scm

@@ -356,7 +356,7 @@ respectively."
 (define* (latest-release package #:key (version #f))
   "Return an <upstream-source> for the latest release of PACKAGE."
   (when version
-    (error
+    (raise
      (formatted-message
       (G_ "~a updater doesn't support updating to a specific version, sorry.")
       "hackage")))

guix/import/minetest.scm

@@ -22,6 +22,7 @@
   #:use-module (ice-9 threads)
   #:use-module (ice-9 hash-table)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-34)
   #:use-module (guix diagnostics)
   #:use-module ((guix packages) #:prefix package:)
   #:use-module (guix upstream)
@@ -492,7 +493,7 @@ or #false if the latest release couldn't be determined."
   (define source (package:package-source pkg))
 
   (when version
-    (error
+    (raise
      (formatted-message
       (G_ "~a updater doesn't support updating to a specific version, sorry.")
       "minetest")))

guix/import/opam.scm

@@ -29,6 +29,7 @@
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-2)
   #:use-module ((srfi srfi-26) #:select (cut))
+  #:use-module (srfi srfi-34)
   #:use-module ((web uri) #:select (string->uri uri->string))
   #:use-module ((guix build utils) #:select (dump-port find-files mkdir-p))
   #:use-module (guix build-system)
@@ -417,7 +418,7 @@ package in OPAM."
 (define* (latest-release package #:key (version #f))
   "Return an <upstream-source> for the latest release of PACKAGE."
   (when version
-    (error
+    (raise
      (formatted-message
       (G_ "~a updater doesn't support updating to a specific version, sorry.")
       "opam")))

guix/import/stackage.scm

@@ -145,7 +145,7 @@ included in the Stackage LTS release."
       "Return an <upstream-source> for the latest Stackage LTS release of
 PACKAGE or #f if the package is not included in the Stackage LTS release."
       (when version
-        (error
+        (raise
          (formatted-message
           (G_ "~a updater doesn't support updating to a specific version, sorry.")
           "stackage")))