title: flair introduces empty spaces in string when doing NER task
body: <p>I'm working on a NER task using <a href="https://pypi.org/project/flair/" rel="nofollow noreferrer">flair</a>. I noticed that sometimes flair introduces empty spaces after processing a sentence.</p>
  <p>Example: the input sentence <code>Herman Melvilles email is mobydick123@gmail.com ;-)</code> gives as output <code>[PERSON_NAME] email is mobydick123 @ gmail.com ;-)</code> instead of <code>[PERSON_NAME] email is mobydick123@gmail.com ;-)</code>.</p>
  <p>How can I fix that?</p>
  <pre><code>from flair.data import Sentence
  from flair.models import SequenceTagger
  import re
  tagger = SequenceTagger.load(&quot;flair/ner-english-ontonotes-large&quot;)
  
  line = 'Herman Melvilles email is mobydick123@gmail.com ;-)'
  
  sentence = Sentence(line)
  tagger.predict(sentence)
  ii = 0
  sentence1 = sentence
  if len(sentence.get_spans('ner')) &gt; 0:
      for entry in sentence.get_spans('ner'):
          if 'PERSON' in str(entry):
              person = re.findall('&quot;([^&quot;]*)&quot;', str(entry))
              sentence1 = str(sentence1).replace(str(person[0]), &quot;[PERSON_NAME]&quot;)
       
              # Return the output sequence 
              try:
                  sentence1 = re.findall('&quot;([^&quot;]*)&quot;', sentence1)[0]
              except: 
                  sentence1 = line
          else:
              sentence1 = line
  
  print(sentence1)
  </code></pre>