Error handling

bk.nim

@@ -21,10 +21,24 @@ const
   ]
 
 proc loadConfig(configFile = defaultConfigFile): Config =
-  defaultConfigFile.readFile.parseJson.to(Config)
+  try:
+    defaultConfigFile.readFile.parseJson.to(Config)
+  except IOError:
+    stderr.writeLine "Error: Can't read the config file. Are you signed in?"
+    quit QuitFailure
+  except JsonParsingError, JsonKindError:
+    stderr.writeLine "Error: Invalid config file. Make sure it's in JSON format."
+    quit QuitFailure
+  except KeyError:
+    stderr.writeLine "Error: The config file doesn't contain all necessary fields."
+    quit QuitFailure
 
 proc saveConfig(configFile = defaultConfigFile, config: Config) =
-  configFile.writeFile((%*config).pretty)
+  try:
+    configFile.writeFile((%*config).pretty)
+  except IOError:
+    stderr.writeLine "Error: Can't write the config file."
+    quit QuitFailure
 
 proc signin(
     website: string,
@@ -71,17 +85,21 @@ proc timetable(
       line &= lesson.room.abbrev.align(4)
       stdout.writeLine line
 
-dispatchMulti(
-  [signin, help = {
-    "website": "the URL for Bakaláři (e.g. https://bakalari.myschool.cz)",
-    "username": "your username",
-    "password": "your password (will not be stored anywhere)",
-    "config-file": "where to store the credentials",
-  }],
-  [timetable, help = {
-    "config-file": "where the credentials are stored",
-    "date": "any date inside the week you want to display, in YYYYMMDD format (defaults to today)",
-    "one-day": "display only the specified day",
-    "permanent": "display the permanent timetable",
-  }],
-  )
+try:
+  dispatchMulti(
+    [signin, help = {
+      "website": "the URL for Bakaláři (e.g. https://bakalari.myschool.cz)",
+      "username": "your username",
+      "password": "your password (will not be stored anywhere)",
+      "config-file": "where to store the credentials",
+    }],
+    [timetable, help = {
+      "config-file": "where the credentials are stored",
+      "date": "any date inside the week you want to display, in YYYYMMDD format (defaults to today)",
+      "one-day": "display only the specified day",
+      "permanent": "display the permanent timetable",
+    }],
+    )
+except OSError:
+  stderr.writeLine "Error: Generic OS error. Check your internet connection."
+  quit QuitFailure