Catch exception in get_languages() (#387)

When passing a non-existent path.

Author: cjmayo

tesserocr/tesseract5.pxd

@@ -282,7 +282,7 @@ cdef extern from "tesseract/baseapi.h" namespace "tesseract" nogil:
             int Init(cchar_t *, cchar_t *)
             cchar_t *GetInitLanguagesAsString() const
             void GetLoadedLanguagesAsVector(vector[string] *) const
-            void GetAvailableLanguagesAsVector(vector[string] *) const
+            void GetAvailableLanguagesAsVector(vector[string] *) except +
             void InitForAnalysePage()
             void ReadConfigFile(cchar_t *)
             void SetPageSegMode(PageSegMode)

tesserocr/tesserocr.pyx

@@ -2815,7 +2815,11 @@ def get_languages(path=_DEFAULT_PATH):
             int i
     baseapi.Init(py_path, NULL)
     path = baseapi.GetDatapath()
-    baseapi.GetAvailableLanguagesAsVector(&v)
+    try:
+        baseapi.GetAvailableLanguagesAsVector(&v)
+    except RuntimeError:
+        baseapi.End()
+        raise
     langs = [v[i].c_str() for i in range(v.size())]
     baseapi.End()
     return path, langs