How does 1-bromo-2-fluorobenzene react with lithium amalgam?
Quoting from Page 1063 of Advanced Organic Chemistry FIFTH EDITION, Part B - 
Reactions and Synthesis, FRANCIS A. CAREY, and RICHARD J. SUNDBERG:


  Benzyne can also be generated from o-dihaloaromatics. Reaction with lithium amalgam or magnesium results in the formation of transient organometallic compounds that decompose with elimination of lithium halide. o-Fluorobromobenzene is the usual starting material in this procedure.
  
  


As @orthocresol said in the comments that Benzyne undergoes Diels-Alder reaction with furan.

The first Diels–Alder reaction of benzyne with furan was performed before giving a 76% yield of the adduct, which was converted to 1-naphthol with acid${^1}$ ${^2}$.



From Diels-Alder adduct to 1-naphthol



In the absence of the furan trapping agent, biphenylene and triphenylene were obtained in yields of 24 and 3% respectively${^3}$.



References

${^1}$:https://www.researchgate.net/publication/273556121_The_Benzyne_Story

${^2}$ :Shashidher et al., Pharm Anal Acta 2011, 2:7
DOI: 10.4172/2153-2435.1000137

${^3}$ :https://www.researchgate.net/publication/273556121_The_Benzyne_Story