Fix logger.exception error when no exception present in Azure log exporter (#1006)

Author: lzchen

contrib/opencensus-ext-azure/CHANGELOG.md

@@ -2,13 +2,22 @@
 
 ## Unreleased
 
+- Fix `logger.exception` with no exception info throwing error
+([#1006](https://github.com/census-instrumentation/opencensus-python/pull/1006))
+
+## 1.0.7
+Released 2021-01-25
+
+- Hotfix
+([#1004](https://github.com/census-instrumentation/opencensus-python/pull/1004))
+
 ## 1.0.6
 Released 2021-01-14
 
 - Disable heartbeat metrics in exporters
   ([#984](https://github.com/census-instrumentation/opencensus-python/pull/984))
 - Loosen instrumentation key validation to GUID
-  ([#984](https://github.com/census-instrumentation/opencensus-python/pull/984))
+  ([#986](https://github.com/census-instrumentation/opencensus-python/pull/986))
 
 ## 1.0.5
 Released 2020-10-13

contrib/opencensus-ext-azure/opencensus/ext/azure/log_exporter/__init__.py

@@ -170,24 +170,35 @@ def log_record_to_envelope(self, record):
             exctype, _value, tb = record.exc_info
             callstack = []
             level = 0
-            for fileName, line, method, _text in traceback.extract_tb(tb):
-                callstack.append({
-                    'level': level,
-                    'method': method,
-                    'fileName': fileName,
-                    'line': line,
-                })
-                level += 1
-            callstack.reverse()
+            has_full_stack = False
+            exc_type = "N/A"
+            message = self.format(record)
+            if tb is not None:
+                has_full_stack = True
+                for fileName, line, method, _text in traceback.extract_tb(tb):
+                    callstack.append({
+                        'level': level,
+                        'method': method,
+                        'fileName': fileName,
+                        'line': line,
+                    })
+                    level += 1
+                callstack.reverse()
+            elif record.message:
+                message = record.message
+
+            if exctype is not None:
+                exc_type = exctype.__name__
 
             envelope.name = 'Microsoft.ApplicationInsights.Exception'
+
             data = ExceptionData(
                 exceptions=[{
                     'id': 1,
                     'outerId': 0,
-                    'typeName': exctype.__name__,
-                    'message': self.format(record),
-                    'hasFullStack': True,
+                    'typeName': exc_type,
+                    'message': message,
+                    'hasFullStack': has_full_stack,
                     'parsedStack': callstack,
                 }],
                 severityLevel=max(0, record.levelno - 1) // 10,