Show proper string in manga detail screen for SourceNotInstalledException

(cherry picked from commit 14d1bcacc9cba0e14cdf90a7972bf85660465c0b)

app/src/main/java/eu/kanade/tachiyomi/ui/manga/MangaScreenModel.kt

@@ -977,6 +977,14 @@ class MangaInfoScreenModel(
             }
         }
     }
+
+    private val Throwable.snackbarMessage: String
+        get() = when (val className = this::class.simpleName) {
+            null -> message ?: ""
+            "SourceNotInstalledException" -> context.getString(R.string.loader_not_implemented_error)
+            "Exception", "HttpException", "IOException" -> message ?: className
+            else -> "$className: $message"
+        }
 }
 
 sealed class MangaScreenState {
@@ -1055,10 +1063,3 @@ val chapterDecimalFormat = DecimalFormat(
     DecimalFormatSymbols()
         .apply { decimalSeparator = '.' },
 )
-
-private val Throwable.snackbarMessage: String
-    get() = when (val className = this::class.simpleName) {
-        null -> message ?: ""
-        "Exception", "HttpException", "IOException", "SourceNotInstalledException" -> message ?: className
-        else -> "$className: $message"
-    }