Make cleaner error message for no config profile

Fixes #484

common/client.go

@@ -149,10 +149,14 @@ func (c *DatabricksClient) configureFromDatabricksCfg() (func(r *http.Request) e
 		return nil, err
 	}
 	if c.Profile == "" {
-		log.Printf("[INFO] Using DEFAULT profile from ~/.databrickscfg")
+		log.Printf("[INFO] Using DEFAULT profile from %s", configFile)
 		c.Profile = "DEFAULT"
 	}
 	dbcli := cfg.Section(c.Profile)
+	if len(dbcli.Keys()) == 0 {
+		// here we meet a heavy user of Databricks CLI
+		return nil, fmt.Errorf("%s has no %s profile configured", configFile, c.Profile)
+	}
 	c.Host = dbcli.Key("host").String()
 	if c.Host == "" {
 		return nil, fmt.Errorf("config file %s is corrupt: cannot find host in %s profile",

common/testdata/corrupt/.databrickscfg

@@ -0,0 +1,5 @@
+[nohost]
+token = PT0+IC9kZXYvdXJhbmRvbSA8PT0KYFZ
+
+[notoken]
+host = https://dbc-XXXXXXXX-YYYY.cloud.databricks.com/

provider/provider_test.go

@@ -303,6 +303,12 @@ func TestProviderConfigurationOptions(t *testing.T) {
 			assertHost:  "",
 			assertToken: "",
 		},
+		{
+			env: map[string]string{
+				"HOME": "../common/testdata/corrupt",
+			},
+			assertError: "../common/testdata/corrupt/.databrickscfg has no DEFAULT profile configured",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(fmt.Sprintf("config:%v env:%v", tt.rawConfig(), tt.env), func(t *testing.T) {