[http- unzip_http] handle errors in retrieving URLs

Make error output user-friendly, instead of showing a traceback.
for errors like: http.client.RemoteDisconnected: "Remote end closed
connection without response" and ConnectionError ("[Errno 104]
Connection reset by peer"). And urllib3.exceptions.MaxRetryError
in get_range() on a closed connection. And HTTP status codes other
than success in the zip file HEAD request.

visidata/loaders/http.py

@@ -1,4 +1,5 @@
 import re
+import http.client
 
 from visidata import Path, RepeatFile, vd, VisiData
 from visidata.loaders.tsv import splitter
@@ -55,6 +56,8 @@ def openurl_http(vd, path, filetype=None):
         vd.fail(f'cannot open URL: HTTP Error {e.code}: {e.reason}')
     except urllib.error.URLError as e:
         vd.fail(f'cannot open URL: {e.reason}')
+    except (http.client.HTTPException, ConnectionError) as e:
+        vd.fail(f'cannot open URL: {e}')
 
     filetype = filetype or vd.guessFiletype(path, response, funcprefix='guessurl_').get('filetype')  # try guessing by url
     filetype = filetype or vd.guessFiletype(path, funcprefix='guess_').get('filetype')  # try guessing by contents

visidata/loaders/unzip_http.py

@@ -149,7 +149,13 @@ def namelist(self):
         return list(r.filename for r in self.infoiter())
 
     def infoiter(self):
-        resp = self.http.request('HEAD', self.url)
+        urllib3 = vd.importExternal('urllib3')
+        try:
+            resp = self.http.request('HEAD', self.url)
+        except urllib3.exceptions.HTTPError as e:
+            vd.fail(f'cannot open URL: HTTP Error {e}')
+        if not (200 <= resp.status <= 299):
+            vd.fail(f'cannot open URL: status code {resp.status}')
         r = resp.headers.get('Accept-Ranges', '')
         if r != 'bytes':
             hostname = urllib.parse.urlparse(self.url).netloc
@@ -231,7 +237,11 @@ def extractall(self, path=None, members=None, pwd=None):
             self.extract(fn, path, pwd=pwd)
 
     def get_range(self, start, n):
-        return self.http.request('GET', self.url, headers={'Range': f'bytes={start}-{start+n-1}'}, preload_content=False)
+        urllib3 = vd.importExternal('urllib3')
+        try:
+            return self.http.request('GET', self.url, headers={'Range': f'bytes={start}-{start+n-1}'}, preload_content=False)
+        except urllib3.exceptions.HTTPError as e:
+            vd.fail(f'cannot open range for URL: HTTP Error {e}')
 
     def matching_files(self, *globs):
         for f in self.files.values():